The invention relates to a pressure roller with a non-rotatably mounted axial support about which a roller shell is capable of rotating, the said shell being supported on the support in a supporting plane by hydrostatic supporting elements, and being rotatably mounted and guided both axially and radially at both ends by means of a guide ring in each case arranged at the roller shell edge, the said ring being non-rotatable relatively to the support but capable of displacement axially and along the supporting plane.
Pressure rollers of this kind are known for the pressure treatment of webs of material such as for example paper. Under load, the support bends and thus deviates from the axis line of the roller shell. But the guide rings remain on the axis of the roller shell, since they are capable of displacement along the supporting plane and axially relatively to the support. According to a known constructional form, the guide rings comprise an elongated aperture with guide surface which are arranged symmetrically relatively to the supporting plane and are guided along flat portions constructed symmetrically relatively to the supporting plane on the support. The flat portions also allow axial displacement of the guide rings relatively to the support. The guide rings can also tilt relatively to the support and thus remain at right angles to the axis of the roller shell when the support bends under load.
To hold the guide rings in a desired axial position relatively to the support, hitherto blocks or pins have been provided which were supported for example on the support and limited axial displacement but did allow the tilting of the guide rings relatively to the support.
This hitherto known construction described hereinbefore was found to be satisfactory with pressure rollers having metal shells. In contrast, difficulties were encountered when using elastomeric roller shells. The fact is that these cannot be produced with the desired precision achieved with metal shells and also are found to be subjected to certain variations in dimensions when under load. All this results unavoidably in the case of elastomeric roller shells in non-circular running, particularly at the edges. This untrue running is transmitted to the guide rings, which are forced to wobble relatively to the support. This wobbling results in premature wear on for example the blocks or pins, or the guide surfaces of the guide rings, or the flat portions on the support respectively, and has resulted for example in the guide ring knocking against the support.